… in a nearby open space preserve on the San Francisco peninsula the other day, I came across a somewhat mysterious sign.

I figured this must mark something pretty impressive, because it’s just out in the middle of a field near a nice trail.

Even more strangely, when I turned around and looked south east from this marker, I saw the following hillside:

You can see the trail, and then on the hillside across the little valley, I can see two parallel tracks. They look like trails, but when I went over there, I found a fence blocking my path with a “no trespassing” sign. Huh.

Naturally, I’m curious. Can you help me figure out what’s going on here?

This week’s Challenge is about starting with one piece of information and then working from that to another, and another, and another.

1. What does this sign indicate? Why would someone post this in the middle of an empty field?

2. What’s up with the two trails to the south? Why are they there?

3. Can you figure out why that small caution sign is there in the middle right of the first picture above?

Any ideas? I found this to be pretty interesting, in part because I had no idea what these kinds of signs are all about, and it opened up a whole new whole of things I’d never thought about before.

Hope you find this Challenge equally engaging.

When you figure it out, be sure to tell us HOW you found out!

Search on!